Many separating devices employ a screen over which material is moved so that the smaller particles may pass through the screen while the larger particles pass therealong. Such screens are often subject to excessive wear and are subject to damage due to the clogging of the screen by the particles themselves. Furthermore, the material must often be recirculated over the screen in order to effectively filter out a high ratio of particles of the size attempted to be separated therefrom.
To overcome this problem, a separator with a plurality of screens, preferably inclined and overlying each other in series, was proposed in U.S. Pat. No. 3,232,431. While highly satisfactory for its intended purpose, there has remained a need for a material separating or classifying apparatus for difficult materials which would catch in typical wire mesh or perforated screen type devices. Specifically, there are a number of difficult materials that are not readily separable by any apparatus that is presently commercially available.
In this connection, it would be desirable to be able to classify or separate such materials in a continuous process. Among the materials to which this would apply, and by way of example only, is shredded auto scrap residue, building demolition materials, wood refuse including bark, municipal solid wastes, solid-fluid mixtures, biomass fuels, and the like. For all such materials, the apparatus should be non-bending, self-relieving, and stay clean without "porcupining."
The present invention is directed to overcoming the above stated problems and accomplishing the stated objects by providing a unique material separating apparatus.